First of all, congrats for your offers! Your position is a very good place to be.
Needless to say that no one here can make the decision for you, however I think what you choose will depend on what you want and value more.
Do you want a change in lifestyle, live somewhere else and experience a new culture? This for me would be the key question, together with whether I plan to do an MBA or not. As the latter will also influence where you will end up living at some point. Everything else is possible to sort afterwards. Let me explain, I have very close friends that have started their careers in Dubai in Tier 2, moved to MBB in Dubai, pursued a sponsored MBA in the US and now pursuing an internship there. I have other friends which instead started off in MBB in Dubai and decided to come back after 2 years in London, they either decided to transfer office or pursue industry after deciding consulting wasn’t for them.
Finally, if you want to and have the skills, you can always move to MBB 1,2, 3 years in the job either from Tier 2 but also Tier 3, for example I have few friends that got into MBB London after 1-2 year experience in boutique firms.
In summary, I would consider your partner and current friends, your desire to experience new things and pursue an MBA and the implications that these choices could have on your life in the next 2-3 years. After having clarified those, your career choices should just support your objective in my opinion and not the other way around.
Just a note on ME vs. London, I think the former involves more frequent travel particular in Saudi and other close markets and several key projects are inevitably public sector focused (or sponsored), working hours I would say are comparable, although ME I believe has more top-down / hierarchical work environment than that in London based on my project experience there.
Hope it helps!
When you say needing to know someone from the MBB London office, would this need to be someone higher up eg partner?